There are leaves on the line and the traffic jams are worse than ever. The prospect of working from home is increasingly enticing.

You need the right type of work and equipment to operate at home, but you also need the right location. Should you take over a spare bedroom, make use of that redundant garden shed, or even buy a purpose-built office cabin? More important still, are you thinking about what will add most value to your house - or at least detract from it as little as possible?

External, pre-fabricated offices are now all the rage. Different makes are begin ning to appear on the market following the success of Ardis, a Devon company making self-contained office units designed for gardens, courtyards or work sites.

Externally they look like beach huts and are available in up to 50 different colours. Inside they have the desks, shelving, and power points for a conventional office. Prices start from just under £7,000 for a floorspace of 48 sq ft to almost £10,000 for 144 sq ft, and include construction costs for people afraid of the ultimate DIY self-build task.

If you want a cheaper option, use the old garden shed and arrange for the sort of electrical fittings, weather-proofing and heating which would make long periods of work realis tic and comfortable.

An external home office - purpose-built or modified - may seem expensive but, ironically, this is more likely to produce a good return when you sell your home, experts say.

'You certainly could fit out a shed or outbuilding and probably get your money back - in fact it would make the space look more like a proper room, albeit one step removed from the main house,' says Devon estate agent Peter Aldiss. 'Depending on the original size of the house, this could add upwards of £20,000.'

Fitted offices in a spare room are becoming more popular - these are the up-market alternatives to buying flat-pack office furniture and simply placing it on floors and against walls.

Fitted offices are expensive. Four suppliers quoted 'average' order prices from £6,000 to £10,000, covering hardwood structures which were mostly off the shelf but involved some tailoring to fit awkward corners or roof areas.

Selling a house when one or more rooms has been set aside for office use usually incurs no additional cost, provided the house is your main or sole residence. But very occasionally the Inland Revenue can assert that because the house is part-used for business purposes, at least a proportion of the 'profit' made on its resale can become liable for Capital Gains Tax.

Accountants advise that there is a simple way to avoid the problem - instead of routinely setting against tax a full 100 per cent of the costs associated with the 'business' room in the house, nominate a smaller figure (80 per cent, for example). Although this may involve a marginally higher tax payment during yearly self-assessment, it will probably avoid any issue of CGT being applied.

But will an office really add value to a house? Probably not, say the experts.

'If someone can cleverly design a spare room to maximise its flexibility so it can be used as an office or a spare bedroom, this can definitely increase the marketability, and possibly add 5 per cent to its value. But it needs to be flexible and able to revert to another use,' explains Ed Mead from estate agents Douglas and Gordon. 'It's only when a spare room is completely fitted out so it can only be an office that it may actually detract from the value.'

Even some players in the fitted office market accept the point. 'If you're staying in a property for a short time, such an outlay probably won't add value,' admits Jim Gettings of Neville Johnson office fitters. 'But it offers a real compromise for home living.' Terry Harkin of Leeds-based office fitter Harkin and Barker adds: 'The key is to ensure it's made of high-quality products, is not too avant-garde in design and is not too personalised.'

Whichever option you go for, this change to your house will be one of the few that you can look forward to declaring to the Inland Rev enue. Whether you are an employee or self-employed, many of the modifications to create a home office can be offset against tax. But bear the following points in mind before you take the plunge:

· Planning permission is not needed if the 'character and use' of the house stay essentially residential.

· You can also use the garage in your house to repair a car used in connection with your work.

· The work going on at your house must not cause nuisance or inconvenience to your neighbours.

· But if neighbours do complain to your local council, the planning department is obliged to look at the appropriate planning permission given to your house - and can inspect the property with 24 hours notice.